Free calculator
50% rule calculator
Screen a rental’s cash flow in seconds. The 50% rule assumes operating expenses run about half of gross rent; enter the rent and mortgage payment for a quick, rough read.
The short answer
Last updated: July 2026
The 50% rule is a screening rule of thumb: assume a rental’s operating expenses run about half of gross rent, then subtract the mortgage payment to estimate cash flow. On $2,600 rent, it pegs expenses near $1,300, so a $1,200 mortgage leaves roughly $100 a month. It’s a fast filter, not real underwriting.
After the estimate:
Self-management software50% rule calculator
A quick cash-flow screen for a rental.
The 50% rule assumes operating expenses run about half of gross rent. Enter the rent and the mortgage payment for a fast, rough read on monthly cash flow.
Monthly gross rent
$
Monthly mortgage payment (P&I)
$
Principal and interest only — the 50% estimate is meant to cover taxes, insurance, and upkeep separately.
Input-driven result
Your inputs
Formula
Result below
Estimated monthly cash flow
$100
Rent $2,600 − 50% expenses $1,300 − mortgage $1,200.
Estimated operating expenses
$1,300
The rule's assumption: about 50% of gross rent goes to operating costs (not the mortgage).
50% rule cash-flow screen
Monthly rent
$2,600
Estimated operating expenses
-$1,300
Mortgage payment
-$1,200
Estimated cash flow
$100
Estimate based on your inputs. Not a promise of results.
The 50% rule is a screening rule of thumb, not a substitute for real numbers. Actual expenses vary widely with age, taxes, and management. Use it to filter deals quickly, then verify with itemized figures.
How it works
How this tool works.
The 50% rule is a shortcut investors use to screen deals before digging into real numbers. It assumes that, over time, operating expenses — everything but the mortgage — eat about half of gross rent. That single assumption turns a listing into a rough cash-flow read in seconds.
Enter the monthly rent and your mortgage payment, and this calculator applies the rule for you: half of rent set aside for expenses, the rest weighed against the loan. Treat the result as a first-pass filter, not a substitute for itemized costs.
Make the result useful
Fifty-percent-rule screening
Gross rent is the recurring income used for the quick expense placeholder.
The 50% factor is a screening assumption for operating expenses before debt.
Mortgage debt service is intentionally excluded from the placeholder.
Actual expense history should replace the shortcut whenever available.
Calculation lens
operating-expense placeholder = gross rent × 50%
Use the output as a documented scenario result, not a guarantee.
Not a property-specific expense forecast.
Questions landlords ask
Questions about this tool and its limits.
Built by a landlord who's done every one of these jobs by hand.
Aptoria was built by an owner-operator managing a Brooklyn portfolio — the 11pm calls, the awkward rent texts, the April receipt-pile — not by a software team guessing at the problem.
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